http://newton.physics.wwu.edu:8082/jstewart/scied397/brian.html

Species Extinction:
A Human Endeavor?

By: Brian Shirley

Spring, 2000

Introduction

"The human species is our own home-grown asteroid."
E.O. Wilson (Biology, 1996, p. 485)

This statement reflects growing concern that our planet is
undergoing a rapid loss of biodiversity due to extinction.
The popular media has quoted statistical evidence that we are
losing species at a rate much higher than the hypothesized
asteroid that caused the great Cretaceous Extinction. What
are the causes of this rampant loss of diversity from our
planet? Homo sapiens are frequently blamed without significant
evidence cited or what specific human actions are related
to these higher extinction rates. Although the evidence is
generally lacking in the popular media reports, the scientific
community has long chastised us for the decimation of species.
Exploring through the scientific data is necessary to arrive at
any logical and supported conclusions. An attempt is made here
to determine if extinctions are occurring at a high rate, what
are the causes, and what can the human population do, and
why is biodiversity important enough to invest efforts
to control extinction rates. It is then up to the reader
to determine whether current extinctions are a human endeavor.

History of Extinction

The world has encountered significant species loss in the past,
long before humans were even an evolutionary dot on the horizon.
Extinctions are natural course of history and from the fossil
record we hypothesize that only .1% (Extinction, April, 00)
to 5% (Global Biodiversity Assessment, 1995 p. 197) of all
organisms ever to walk the earth are alive presently.
Earth's biotic environs have certainly undergone changes
and turnovers since life began three and a half billion
years ago (Biology, 1998). Paleontologists have postulated
through evidence in the fossil record that there has been
approximately five "mass extinction's" throughout geologic
time (although a sixth one in the Cambrian has now been
postulated) (Biology, 1998). These mass extinctions are
defined by scientists as the loss of 40% to 95% of the
fauna living at the time before the decline of biodiversity
(Insights, April, '00). These include:

Name Time (millions of years ago, mya) % of species lost

Ordovician-Silurian 439 mya 85%

Devonian 345 mya 85%

Permian 253 mya 90%

Triassic 213 mya 76%

Cretaceous 65 mya 85%

(From Extinction, April, '00 and Biology, 1998)

Another extinction of noteworthiness is the Pleistocene Extinction
of large birds and mammal species. These occurred approximately
20,000 years ago (Extinction, April, '00) but it is unknown
how much significance human’s role was in those extinction's.

Most scientists have recognized that extinction is a necessary
element of evolution. Following a mass extinction, species
that previously had insignificant numbers of the total percentage
of fauna and flora were allowed to radiate out (Insights,
April, '00). The mammal radiation after the Cretaceous-Tertiary
Extinction is a perfect example. After the dinosaurs had died out,
the fossil record clearly shows a huge increase in mammalian
species. Without the decimation of the large, widely dispersed,
dominant reptiles, mammals might have remained the small,
subversive species it was previous to the extinction.

So why then, if extinctions are integral in the evolutionary
processes should humankind be worried? Humans dominate
the landscape just as the dinosaurs did in the Cretaceous.
Therefore, if we apply similar biological concepts
to ourselves (although many would argue that these
do not apply to us), we are threatened in the same
manner. The significant differences, however, are that,
1) we could be the cause of the extinction, and
2) we have the ability to at least change the way
we affect biodiversity and its declination.

Extinction Rates

Statistics and numbers get thrown around tremendously in our
contemporary media. Most people do not even know how to read,
interpret, or be skeptical of these number "facts". With
this in mind, the media and scientists simplify complicated
data into a number that is easy to recognize for most people.
The major problem lies not within the number itself, but
the question of how the scientist came up with the number.
The majority of people do not question numerical statistics,
but the analytical, probing mind begs to know the reasoning
and methodology behind the figures.

How can biologists, ecologists, and taxonomists determine the
current extinction rates? E. O. Wilson states in an article
that "... it is notoriously difficult to estimate the overall
rate of extinction" (Only Humans. . ., April, ’00 p. 2).
With roughly only 1.5 million species known and catalogued
and an estimate of 10 to 50 million species currently living
on earth (Campbell, 1996, p. 485), most species that become
extinct are not even known to humans. It is widely hypothesized
that most extinction’s occur in the tropical forest regions
of earth because the majority of terrestrial species live in
these areas (Global Biodiversity: Status of the Earth’s Living
Resources, 1992). Most extinctions are therefore presumed to
be arthropod species living in these environments (Global
Diversity, 1992). Using these assumptions scientists equate
habitat destruction (especially in tropical forests) to
species extinction. (Extinction, April, ’00), (Life, 1998,
p. 1224), (Global Biodiversity, 1992, p. 202-204)

There are several mathematical models that attempt to quantify
this complicated issue. Obviously, there are numerous assumptions
that are made in order to make these calculations possible.
The broadest and most underlying assumption is that species
are distributed evenly throughout habitats. Other assumptions
are that deforestation figures are accurate and presume a
general increase in these rates in the future. Also, models
generally do not take into account extinctions that occur
long after the habitat is destroyed, or residual extinctions.
Also, they don’t attribute extinctions caused by island
biogeographic’s (that is "islands" of habitat will suffer
an increase of further extinction rates because the ecology
of one area can be dependant on other nearby areas).
(Global Biodiversity, 1992) An example of one such equation
is (logS=c+ zlogA) where S is the number of species,
A is the area. C and z are constants related to deforestation
rates and the amount of increase in these rates over time.
(Global Biodiversity, 1992) The assumptions are vividly
illustrated in this equation but until further studies
are completed this is the best approximation scientists
make. They try to account for the assumptions by making
the numbers of deforestation and biodiversity densities
as small as possible within a given range.

Current extinction rates are usually based against a
background extinction rate number (Extinction, April, '00).
This "normal" rate is established from looking at the fossil
record and determining the mean average of life spans of
animals. This rate has been estimated that two to five
families of marine invertebrates and vertebrates will
go extinct every million years (Extinction, April, '00).
Another estimate holds that a species average life span
on earth is somewhere between one and ten million years
(Global Biodiversity Assessment, 1995). Though these
numbers differ in their relativity and scope, they both
illustrate that "normal" species extinction is fairly
low on average from what we can extrapolate from the
fossil record.

Biologists and ecologists mostly agree that the current
rate of extinction is higher than the background rate.
(Only Humans. . ., April, ’00) There is considerable
disagreement in just how high above the background rate
we are currently experiencing. These vary from 40 times
the background rate (Extinction, ’00) to 100 times (Only
Humans. . ., April, ’00) to as much 1000 times (Rainforest
Action Network, April, ’00). These numbers are projections
using mathematical models such as explained previously and
are subject to assumptions already discussed. However,
documented cases since c. 1600 have found that 484 animal
species and 654 plant species have become extinct. (Global
Biodiversity Assessment, 1995) This number is well documented
and verifiable and it is well above the projected background
rate.

The World Conservation Union (IUCN) compiles vast amounts
of data on endangered and threatened species around the world.
This list, known as the Red List, documents statuses of animals
and plants. It illustrates the dire need of conservation and
preservation to protect these species. The Red List only
includes species that have been studied by scientists around
the world. There are many species that are not included
because they have not been studied, results of data are
not available, or they haven’t even been identified and
catalogued yet. It is important to note then that these numbers
could be significantly different than overall numbers for total
species. This is because threatened species are more likely
to come under scientific study than non-threatened species
but many species are not even known to scientists yet.

These are some numbers from the IUCN’s Red List:

25% of mammal species threatened 20% of reptiles

11% of bird species 34% of fish

12.5% of all plant species

(Data from New York Times Article, April 9, 1998 & Animals in the Red, 1996)

We must not assume that all these threatened and extinct species
come from underdeveloped nations or are just located to tropical
forests elsewhere. The United States (excluding Hawaii whose
numbers would double these) has had 68 species of animals
since c. 1600, the most out of any other region (again,
excluding Hawaii who has 86). (Global Biodiversity, 1992)
Washington State alone has 18 species currently listed as
endangered. (EndangeredSpecie.com, Washington)
Clearly, the U.S. has just as much work to do on conservation
as every other country.

Causes of Extinction

"We aren’t sure who is cutting our forests and who is going
to flood our land, but we know they live in towns, where
rich people are getting richer, and we poor people are
losing what little we have."

(Statement of the Iban People, Sarawak, Malaysia,
Losses of Biodiversity and Their Causes, 2000)

To better understand why these rates are increasing it is
important to look at the why of the issue. Species become
extinct by two main ways. These can be defined as deterministic
processes and stochastic processes. (Global Biodiversity, 1992)
Stochastic processes refer to those that are random, such as
reproduction, survival, environment (weather, food, disease,
floods, and fires) and genetic mutation. (Global Biodiversity,
1992) Deterministic processes refer to cause and effect
relationships such as human habitat destruction.

Humans cannot change or alleviate stochastic processes
for the most part. These are natural changes in populations
that are left to chance for the most part. Genetic mutations
and reproduction are absolutely random but humans are
influencing other stochastic processes such as climate
changes. These are notoriously hard to pinpoint the causes
and the overall effect on species. Deterministic processes,
however, are very controllable and identifiable from a human
standpoint. Humans affect the environment two different
ways, through direct and indirect measures. Direct measures
include exploitation of wild resources, introduction of
species, pollution, climatic changes, and habitat fragmentation
and destruction. Indirect measures include the way we live,
economic values, and human population growth. (Global
Biodiversity, 1992) (Causes of Endangerment, 2000)
(Extinction, 2000)

Habitat destruction or altering is the biggest hypothesized
reason for current accelerated extinction rates. (Special
Feature, 2000) (Rainforest Action Network, 2000) (Extinction,
2000) (Global Biodiversity, 1992) It is estimated that 2%
of rain forest areas are being destroyed each year. (Extinction,
2000) Logging, mining, and urbanization all contribute to the
decrease of our wild lands. Besides destroying the habitat,
these changes occur at such an accelerated pace compared to
natural evolution that it does not allow species to adapt
to new environments slowly enough. (Causes of Endangerment,
2000) Pollution is affecting habitats by changing or
destroying habitats at an accelerated pace as well.

Hawaii and Australia are probably the best-documented
cases involving the introduction of exotic species that
has a negative affect on the indigenous populations of
wildlife. In Australia they introduced rabbits, foxes
and cats. It is estimated that half of the indigenous
marsupials have since become extinct because of this.
(Life, 1998) Exotic species effect environments two ways,
1) they can become predators of native species, or
2) they can out-compete native plants and animals for
food thus destroying the delicate ecological balance.
(Causes, 2000)

Overexploitation of wildlife is another direct measure
humans have employed to cause extinctions. The hunting
of whales and seals in the early 1900’s brought populations
of numerous species to low levels. Elephants and rhinos
have been hunted for their tusks and horns, severely reducing
their numbers. Today, the salmon of the Pacific Northwest
(especially Snake River populations) are endangered from
overexploitation (habitat destruction by the building of
dams is also a major cause). The American buffalo and bison
herds were decimated by white settlers and on Hawaii,
at least 39 species of birds have become extinct since
Polynesian settlers first landed. (Life, 1998) (Extinction,
2000)

Indirect methods of human induced extinction involve more
subtle measures that aren’t as obvious or immediate.
They include rapid and exponential population growth,
resource consumption, international trading and transportation,
and inability of economic systems to protect and value the
environment. As our population grows, more land and resources
are needed to feed it and to live on. Humans now are probably
the most numerous large mammals. (Insights, 2000) Apart from
being the most numerous, Homo sapiens are one of the most
resource demanding species ever to walk the earth.

Economists say that this growth can continue indefinitely
with biologists vehemently arguing the opposite. (Insights,
2000) Humans are driven by short-term personal goals that
are clearly (from a biological standpoint) in direct
opposition to the goals of the whole species. Economists
say that there is no upper limit to human growth and
market forces, or the economy, will be the determinate
of the upper limit. They postulate that supply and demand
will govern human populations by limiting resources and
products where needed. It is easy to see that this apparent
logical argument is erroneous however. Supply and demand
is now being manipulated artificially by the market that
is supposed to restrict it. For example, oil prices have
not increased significantly in recent history (especially
in the United States) even though it is a non-renewable
resource that possibly will be gone in the future. The
market is now governed by the short-term goals and benefits
of individuals with money and with advertising campaigns
designed to provoke the greed and materialism of the
consumer. (Insights, 2000)

Species survival from a biological point of view depends
greatly on the health of the environment. Biologists predict
and warn that the upper limit of a population is governed
by the carrying capacity of the environment. They say that
humans have already exceeded the world’s carrying capacity.
Technology has allowed humans to create an artificial
carrying capacity by increasing food output through
fertilization and pesticides for example. The decimation
of human population is imminent biologists think because
all of humanity is standing on an ecological platform of
human creation. Think of it in these simplistic terms.
If a rabbit population grows indefinitely and eats and
tramples all the grass around its habitat, then that
population would be hard pressed to survive. There would
be food shortages and increased predation, for the rabbits
would have to travel farther for food and there would
be less hiding places. Humans don’t just trample the
environment, we proceed to pour concrete over it,
pollute it, burn it, use vast amounts of resources, etc.

Species Vulnerability

Not all species or populations respond to their environments
in the same manner. Comparing ecosystems and interpreting
past extinctions, scientists can define certain characteristics
of species or populations that can be at greater risk to
extinction. Species who are at high trophic levels,
those with restricted ranges, have small populations,
are the largest member of a guild, colonial nesters,
or migratory species are all susceptible to extinction.
(Extinction-Prone Groups of Species, 2000) (Global
Biodiversity Assessment, 1995) This list is not inclusive
but these indicators are important if humans are to
identify at risk species and take appropriate conservation
measures.

Trophic levels are terms biologists use to define different
levels of the food chain. Species that are high on this
chain tend to be bigger animals who are not numerous and
have slow reproduction rates. These organisms also depend
on the stability of lower chain levels. Examples of current
threatened species who occupy this status are the Steller’s
sea cow (Hydrodamalis stelleri) and the Tasmanian wolf
(Thylacinus cynocephalus). (Extinction-Prone, 2000)

Correlated with the trophic level are small population
densities of a species and being the largest members of
a guild. Small populations do not have the genetic diversity
or the outright numbers to survive serious habitat depletion
where large numbers can provide some insulation of the
harmful effects. Some tree species within tropical regions
can occur in low numbers, thus whole populations can be
wiped out with deforestation. Guilds refer to groups of
species that share similar food sources. (Extinction-Prone,
2000) The largest member of a guild, as with trophic levels,
are bigger animals with high metabolic needs and occur in
low numbers in an area are more at risk to extinction.

Endemics are the given area a species travels in a
natural environment. Species that have small range
areas are unable to move to new locations if disturbed
by outside forces. This idea is directly related to the
idea of island biogeography and the devastating island
extinctions on Hawaii and Australia mentioned previously.
Many aquatic species, such as the Devil’s Hole pupfish
(whose lives in a spring typically 3 by 15 meters
(Extinction-Prone, 2000)), live in areas where their
endemic is naturally delineated. Similarly, dispersal
ability is an organisms ability to enlarge home ranges
or migrate small distances to move between fragmented
home environments. This could be exemplified by organisms
that can now cross from a wooded area to another wooded
area, through a clear-cut, that were previously
interconnected. Or species, threatened by a warming
climate, disperse into colder climates.

Species with colonial nesting habits or those who migrate
are also susceptible to higher extinction rates. Colonial
nesters such as the Passenger Pigeon (who became extinct
in 1914 (Extinction-Prone, 2000)) are particularly exposed
to overexploitation and loss of habitat. Their nesting
habitats are generally confined to locales of small size
that contain certain environmental conditions for reproduction.
In such large densities, they are easy prey for predators
and with such a specific environment, the habitat loss of
nesting sites can be devastating to large numbers, even
whole populations.

Many other factors can be attributed to increased species
vulnerability. Species who have low adult survival rates
or short-lived adulthood’s can be susceptible. Also organisms
who are highly specialized or feed on food sources that are
unreliable or fluctuate greatly (or species themselves
fluctuate greatly in numbers) increase their potential
for extinction. And finally, species with no previous
contact with humans tend not to be able to adapt to the
new situation fast enough for survival once people begin
to infringe on their habitats. Species or populations
exhibiting any of these characteristics need to be carefully
managed and protected. Small deviations in these natural
environments could have significant and negative affects.

Why is Biodiversity Important

Who cares? This question is repeated over and over again
to every new report or scientific study. The statistics
and numerical extrapolation data can surely be questioned.
Debates will be waged over rates of pollution, deforestation,
mining, climatic change, ozone depletion, fragmentation and
island biogeography, etc. The majority of scientists can agree
on two things however; the rate of extinction is higher than
the normal background rate and humans are the main cause.
But this question is formulated by the individual who is
ready to accept the values and just simply wants to know
just why is biodiversity important.

It is true that extinction has its place in natural selection
and that most species who have lived on this planet or no more.
However, at no time in the history of this planet has one
species utterly dominated the landscape to the point that
all of nature is subjected to serve him. If we are causing
the damage, we should care, as we are part of nature, and
as such subject to extinction ourselves.

The health of ecosystems depends greatly on the amount of
biodiversity. (Only Humans. . ., 2000) It has been shown
that the greater the diversity of life within an ecosystem,
the more resistant it is to catastrophes such as droughts,
fires, and floods. The greater the genetic diversity within
an area, the better the chances that most organisms will
cope and survive. In addition, higher biodiverse areas tend
to be more productive. (Only Humans. . ., 2000) The tropical
forests are perfect examples where roughly 50%-90% of current
species live. (Losses of Biodiversity. . ., 2000) These
areas house many different species and the estimated biomass
is tremendous. The genetic diversity from tropical forests
also provides additions to domestic crops to make them more
resistant to insects and environmental changes. (Rainforest
Action Network, 2000)

As medicines treat and protect us from bacteria and disease
they are unconsciously causing those organisms to evolve.
Soon, it is estimated that current antibiotics and other
medicines will have no or limited effectiveness. Of the
only 1-% of species tested for pharmaceutical value,
approximately 40% of prescription products are substances
originating from living organisms. (Only Humans. . ., 2000)
The rosy periwinkle flower, for example, has recently
found some success in treating some cancers. (Rainforest
Action Network, 2000) More research and testing needs
to be done if humans are to be able to treat the many
pathogens that invade our systems. When these species
disappear, that research and testing cannot be done.

Species diversity is also correlated to many other
positives around our globe. For example native watersheds
clean and filter drinking water. Aesthetics of certain
areas draws tourists from all over, boosting and even
driving some local economies. Protection against soil
erosion and the control of agricultural pests are other
major reasons biodiversity and habitats should be maintained.

Conservation and Conclusion

Conservation biology is dedicated to studying and preserving
biodiversity. (Life, 1998) These scientists look at declining
species and habitat to determine the causes and the best
methods to sustain diversity. They use the ideas of species
vulnerability to determine risks. Two key concepts integral
to conservation are minimum viability population (MVP) and
population viability analysis (PVA). MVP is an estimate of
the number of individuals within a population that will
maintain that population. These are carried out to determine
the health of a species within an area and also to control
numbers of individuals so that they do not overrun an
environment. PVA is the estimated size a population needs
to be to lower or eliminate the risk to extinction. (Life, 1998)

Conservationists are concentrating on two main concepts at this
time using the ideas above. One is surveying and monitoring
environments all across the globe to get accurate data about
species. (Global Biodiversity Assessment, 1995) Inventorying
(surveying) is the starting point for conservation. Gaining
accurate numbers on species numbers and locations is necessary
for studying effects of extinctions. Monitoring is the
assessment of biodiversity changes over time and differentiating
between natural and human induced effects. This is needed to
accurately predict not only extinction rates as a whole but
to decide on areas of high extinction. This leads us to the
second area of concentration for conservationists. This is
the locating "hot spots" of extinction, those highly
susceptible locales, and the preservation of those species
and habitats. (Global Biodiversity Assessment, 1995)

To successfully protect and preserve species, conservation
biologists are in general agreement that habitat protection
is most important. (Life, 1995) (Only Humans. . ., 2000)
Species fare much better in original, undisturbed habitats
than those manipulated by man. An important concept here,
again, is island biogeography. The protected areas must be
connected and whole ecosystems. When we artificially set up
boundaries to preserve and protect species, it is imperative
that we look to natural boundaries and species endemics.
We can’t expect wild animals to follow surveyor lines.

Humans need to intervene sometimes in a more direct manner
than just preserving habitats. Caution must be exhibited
as we do not always understand the full implications our
actions will have in complex biotic environments. Cleaning
up pollution, rebuilding nest sites, the medical assistance
to injured animals, stream rehabilitation, replanting of
deforested areas, induced wild breeding programs, and even
captive propagation are some of the many ways humans can
help sustain diversity. It should be noted however that
some of these examples, such as captive breeding, are
inefficient and have high costs.

Humans have historically put themselves above and beyond
the scope of natural laws citing that if we are intelligent
enough to manipulate nature then we are smart enough to care
and protect it as well. The possibility exists that we are
intelligent enough, but throughout time we have shown
ourselves to be too focused on the short-term.

In order to decrease the current rates of species extinction
we must admit to ourselves four things:

1) We are part of a worldwide biological system subject
to laws of nature

2) Our intelligence and knowledge is not complete in the
mannerisms of these laws

3) Short sightedness generally has severe punishments in
the long run

4) Economics and money will mean absolutely nothing when
mass starvation, hunger, and disease sweeps humanity

The logical argument is that we don’t know exactly what
effects will be produced by our negligence of the environment.
This is true, no scientists can see into the future. I would
rather rely however on natural systems to sustain humanity
than the promise of our intelligence and technology to keep
us safe from disastrous effects of biodiversity loss.

Bibliography

Animal in the Red: Mounting Evidence of Jeopardy to World’s
Species, http://www.iucn.org/wcc/press/animals_in_red.html

A good article for finding numbers and locations of threatened
species around the world.

Biology, 4th edition, Campbell, Neil A., Benjamin/Cummings
Publishing Company, 1996.

This is a college textbook that I find isn’t quite as thorough
and up to date as the Life textbook. It also doesn’t discuss
current issues in as great depth but it is a great resource
for general biology themes.

Causes for Endangerment, http://www.endangeredspecie.com/

This article is about the simple causes that threaten species
across the globe. It is a good resource for an overview of
what humans are doing that is causing the most harm to animals
and plants.

Extinction, http://fig.cox.miami.edu/Faculty/Tom/bil160sp98/10_extinct.html

These, I believe, are lecture notes from a science class.
They were great in summarizing many of the concepts that
were discussed in great depth elsewhere. A good source for
overview information and lots of it.

Extinction-Prone Groups of Species, http://www.wri.org/wri/biodiv/b04-koa.html

This is a good list that outlines major reasons that different
populations are more succesptable to extinction than other groups.

Fact Sheets- Rainforest Action Network, Species Extinction,
http://www.ran.org/info_center/factsheets/03b.html

A good article for summary of facts relating to species
extinction and costs of extinction. One must be careful
to realize that this group is an environmental based group
so the facts from this page are probably gleaned to further
the group’s goals and missions.

Global Biodiversity Assessment, Heywood, V.H., executive chair,
Watson, R.T., chair, Cambridge University Press, 1995.

This book is a huge collection of information relating to the
scientific study of biodiversity. It contains information on
individual species as well as the rationale and methodology
of the assessment of biodiversity worldwide.

Global Biodiversity: Status of the Earth’s Living Resources:
a Report, compiled by the World Conservation Monitoring Centre,
Groombridge, B., editor, London; New York: Chapman & Hall, 1992.

This is a huge collection of scientific studies conducted on
species and habitat conditions by multitudes of researchers
worldwide. Although it is a little hard to navigate through
this large collection, it does provide good information once
found.

"Insights"- Human Population Growth and the Accelerating
Rate of Species Ectinction, Harding, G.W.,
http://www.portalmarket.com/earthportals/extinct.html

This paper deals with how humans, in their consumate
short-sightedness, are threatening our own existence
by decimation of biodiversity. He talks about the economist
vs. biologist debate and provides some facts and studies
to back to biologist postion.

Life: The Science of Biology, 5th edition, Purves, B., Orians,
G., Heller, C., Sadava, D., Sinauer Associates, Inc., 1998.

This is a college level textbook that has been an excellent
resource for many of my projects. It covers all major concepts
that biology encompasses. Of course you wouldn’t read it at
night before going to bed.

Losses of Biodiversity and Their Causes,
http://www.wri.org/wri/biodiv/gbs-li.html

This is another excellent article pertaining to the causes
that threaten and are causing increases in extinction rates.
Many good examples are given here to illustrate real,
current species who are suffering or have become extinct
from these causes.

Only Humans Can Halt the Worst Wave of Extinction
Since the Dinosaurs Died, Wilson, E.O,
http://raysweb.net/specialplaces/pages/wilson.html

E.O. Wilson is one of the prominent and respected advocates
of global conservation. This article summarizes how humans
are destroying the planet along with reasons why we should
be conserving it.

Plant Survey Reveals Many Species Threatened With Extinction,
Stevens, W. K., The New York Times, April 9, 1998 p. A-1,
http://www.well.com/user/davidu/plantextinction,html

This article was good to get numbers of species of plants
who were going extinct as well as locations of those species.

Species: Unprecedented Extinction Rate, and Its Increasing,
By: Simon Stuart

http://www.iucn.org/infoandnews/press/species2000.html

This is an article from the IUCN, reporting the current
trends and causes of species extinction. The IUCN is one
of the most important watchdogs of species protection and
conservation.

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